MRI: Acquisition of Ultrasonic C-Scan System for Research and Educational Training in Structural Nanocomposites

在过去的几年里，纳米复合材料已经成为一种新的材料类别，它可能会给未来的结构部件带来革命性的变化。这些由纳米粒子与聚合物组成的纳米复合材料除了提高阻隔性能外，还在化学、热、机械性能方面表现出了相当大的改善。更令人着迷的是，这些改进发生在纳米颗粒的负载率非常低的情况下。塔斯基吉大学先进材料中心的研究人员成功地将各种纳米颗粒与热固性和热塑性聚合物结合在一起，并将这一概念扩展到制造结构纳米复合材料。通过这种方法，他们实现了强度和刚性的增强，超过了他们的整齐的聚合物复合材料。在这项重大的研究仪器方案中，我们正在寻求一种最先进的超声C扫描系统，以帮助和提高由NSF、ARO、ONR和EPSCoR资助的正在进行的研究项目的各个方面的质量。大量非裔美国学生，包括本科生和研究生，其中许多是博士生，将接受关于新型材料--结构纳米复合材料--的无损表征方面的培训。预计许多年轻的少数民族学生在科学和工程教育的早期阶段，如果接触到最先进的设施，如拟议的超声波C扫描系统，将被鼓励进行研究生学习。结构纳米复合材料具有成为未来材料的潜力，因为与当代纤维增强复合材料相比，它们具有更高的强度和刚度。到目前为止，对纳米复合材料的研究大多集中在改善纳米基质体系的性能上。在塔斯基吉大学先进材料中心(T-CAM)正在进行的研究工作中，正在尝试对纳米结构复合材料进行建模、合成、制造和表征。任何此类开发都需要使用无损评估(NDE)技术来评估制造过程中和不同加载条件下的弹性性能、缺陷和损坏。通过这项提议，我们计划获得最先进的超声无损评估(NDE)系统。利用这一设备，计划通过超声波测量速度和衰减来了解固化动力学，优化使用VARIM工艺制备结构纳米复合材料的工艺，量化制造缺陷，通过非破坏性手段评估新型纳米复合材料的弹性性能，确定纳米复合材料在环境调节下的退化，评估疲劳加载期间损伤的渐进增长，估计低速和弹道冲击加载造成的损伤，以及评估采用VARIM工艺制造整体蒙皮纵梁组件和纤维缠绕等格栅圆柱体过程中产生的缺陷。我们建议通过超声无损检测来表征由不同类型的纳米颗粒、树脂体系和纤维制成的不同类别的纳米复合材料。最后，通过这个项目，大量的非裔美国学生，包括本科生和研究生，其中许多是博士生，将接受关于新材料类别的无损表征的培训：结构纳米复合材料。

In the last few years nanocomposites have emerged as the new class of materials which are likely to revolutionize the future structural components. These nanocomposites which consist of polymers with nanometer-sized particles have exhibited considerable improvements in chemical, thermal, mechanical properties in addition to improved barrier properties. It is all the more fascinating that these improvements occur at a very low loading percentage of nanoparticles. Researchers at Tuskegee University's Center for Advanced Materials have successfully incorporated a variety of nanoparticles with thermosetting and thermoplastic polymers and extended the concept to manufacture structural nanocomposites. Through this approach they have achieved enhancements in strength and stiffness over their neat polymeric composites. In this major research instrumentation proposal, we are seeking to acquire a state-of-the-art ultrasonic C-scan system to assist and enhance the quality of various aspects of the ongoing research projects funded by NSF, ARO, ONR and EPSCoR. A large number of African-American students, both at undergraduate and graduate level with many at Ph.D. level, will be trained in nondestructive characterization of new class of materials, structural nanocomposites. It is only expected that many younger minority students will be encouraged to take up graduate studies when exposed to state-of-the-art facilities like the proposed ultrasonic C-scan system at early stages of their science and engineering education.Structural nanocomposites have potential to become materials of the future as they have potential to have higher strength and stiffness as compared to current generation fiber reinforced composite materials. Most of the research carried out to date on nanocomposites is focused on the improvement of properties of nanophased matrix systems. In the ongoing research work at Tuskegee University Center for Advanced Materials (T-CAM), attempts are being made to model, synthesize, manufacture and characterize nanophased structural composites. Any such development requires techniques to evaluate elastic properties, defects and damages during manufacture and under different loading conditions using nondestructive evaluation (NDE) techniques. Through this proposal, we are planning to acquire a state-of-the-art ultrasonic nondestructive evaluation (NDE) system. Using this facility, it is planned to understand the cure kinetics using velocity and attenuation measurements through ultrasonic means, optimize the process of fabrication of structural nanocomposites using VARIM process, quantify fabrication defects, evaluate the elastic properties of new class of nanophased composites through nondestructive means, determine the degradation of nanophased composites when subjected to environmental conditioning, evaluate the progressive growth of damages during fatigue loading, estimate the damage due to low-velocity and ballistic impact loading and evaluate the defects induced during the fabrication of integral skin-stringer assembly by VARIM process and isogrid cylinders by filament winding. We propose to characterize, by means of ultrasonic NDE, different class of nanocomposites that are made using various types of nanoparticles, resin systems and fibers. Finally, through this program, a large number of African-American students, both at undergraduate and graduate level with many at Ph.D level, will be trained in nondestructive characterization of new class of materials: structural nanocomposites.